Check with Your Doctor

All these things about fasting always say "check with your doctor first"
Pfffftt, most doctors today have no idea about the benefits of fasting...all they know is drugs and operate. So how would they know whether one should go on a fast or not?
The 'check with you doctor' is just said to protect against lawsuits??

Looks like to me, a juice fast would be the absolute healthiest thing you could do for your body. Isn't that right?